AB1514 AN UNUSUAL ASSOCIATION BETWEEN THROMBOTIC THROMBOCYTOPENIC PURPURA AND PRIMARY ANTIPHOSPHOLIPID SYNDROME
Authors: R. Santangeli, G. Montozzi, L. Gamba, S. Salvucci, L. Manfredi, G. Moroncini
Journal: Annals of the Rheumatic Diseases (2022)

Background Thrombotic thrombocytopenic purpura (TTP) is a rare and life-threatening thrombotic microangiopathy characterized by microangiopathic haemolytic anemia, consumption thrombocytopenia and organ injury, particularly kidney failure and neurological manifestation 1 . Two forms are distinguished: the hereditary one, caused by a deficit of the metalloprotease ADAMTS13, and the idiopathic one characterized by the presence of antibodies directed against ADAMTS13. The second one is the most common. There are various subgroups of acquired TTP associated with HIV infection, sepsis, pregnancy, autoimmune disease, disseminated malignancies and drugs. Antiphospholipid syndrome (APS) is a clinical immunological condition characterized by thromboembolic events, repetead miscarriages or stillbirth and thrombocytopenia; it can be a primary disorder or due to connective tissue disease, in particular systemic lupus erythematosus 2 . Objectives We describe a case of TTP associated with a primary APS. The real clinical challenge lies in the differential diagnosis between TTP and anti-phospholipid antibody syndrome. Methods A 37-year-old man presented to the emergency department for short-term episodes of anesthesia of the right upper limb and face with spontaneous resolution. In his past medical history, he suffered of antiphospholipid syndrome treated with warfarin. Upon admission, blood tests revealed severe thrombocytopenia, haemolytic anemia with schistocytes on peripheral blood smear, low thrombin time and prolongation in the prothrombin time. Neurological symptoms were assessed by electroencephalogram and CT brain, resulted negative, while a brain MRI revealed acute-subacute ischemic stroke. Based on these findings we suspected a diagnosis of TTP, subsequently confirmed by reduced activity of ADAMTS-13 with borderline ADAMTS-13 inhibitory antibodies. Immunological testing confirmed positivity of antiphospholipid antibodies and antinuclear antibodies. Results According to the last guidelines3 about management of acute episode of TTP, immediate therapy with high-dose corticosteroids (prednisone 1 mg/kg) and plasmapheresis was started and then we added infusion of rituximab (375 mg/m2/week for 4 times). Efficacy of treatment was evaluated by weekly dosage of ADAMTS13 activity, with a gradual rise in values (3 → 78%) and improvement in symptoms and laboratory examination. After persistent remission, we gradually reduced steroid therapy. Few months later, in February 2021, patient developed a bilateral comunitary pneumonia, that required hospitalization, oxygen - therapy (also with C-PAP) and endovenous antibiotics. After two weeks patient was discharged from hospital in good clinical health and he was subjected to periodic outpatients visits. Disease activity was in remission, so steroid therapy was reduced and recently we added hydroxychloroquine for APS. Some days ago patient developed covid – 19 infection, despite vaccination, and he was treated with monoclonal antibodies, with good clinical response. Conclusion We have described a rare clinical case of TTP, despite concomitant warfarin treatment for primary anti-phospholipid syndrome. A careful follow-up of these medical conditions is recommended for patient’s fragility and for the risk of related serious clinical complications. References [1]Saha M. et al. Thrombotic thrombocytopenic purpura: pathogenesis, diagnosis and potential novel therapeutics. J Thromb Haemost. 2017 Oct;15(10):1889-1900. [2]De Carvalho JF et al. Primary antiphospholipid syndrome with thrombotic thrombocytopenic purpura: a very unusual association. Lupus. 2009 Aug;18(9):841-4. [3]Zheng XL et al. ISTH guidelines for treatment of thrombotic thrombocytopenic purpura. J Thromb Haemost. 2020 Oct;18(10):2496-2502. Disclosure of Interests None declared